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GLYCERINE

463

distilled water. Ether is then added and the whole transferred to a small
separating funnel, the cylinder being rinsed out with ether. After shaking
the water is withdrawn and the ethereal solution allowed to evaporate at the
ordinary temperature in a small dish ; this yields the volatile oil, which may-
be identified by its odour and, it in sufficient quantity, by other characters
To identify nitrobenzene, the ethereal extract obtained in the above
manner is dissolved in a little alcohol and a scrap of zinc and 2-3 c.c. of
dilute sulphuric acid added to the solution. After 2-3 hours the liquid is
filtered into a dish and the filtrate exposed for an instant to chlorine issuing
from a test-tube containing a little potassium chlorate and cone, hydro-
chloric acid : a persistent violet coloration is produced (Armani and Barboni).

Soaps based on coco-nut or palm oil give, with steam, a small quantity of
volatile acids of peculiar odour, which must not be confused with that of soap
containing added perfume.

(e) MEDICINAL SUBSTANCES. Medicinal soaps are made with the most
varied substances, mostly antiseptics, among which are formalin, phenol,
naphthalene, tar,' ichthyol, camphor, sulphur, salicylic and boric acids,
mercury salts, arsenical compounds, juices of medicinal herbs, etc.

These may be tested for by shaking the soap with ether, evaporating
the ethereal solution and examining the residue by suitable methods, or
by dissolving the soap in water, precipitating with barium chloride and
washing the barium soap thus formed with alcohol or ether.

Mercury and arsenic compounds, boric acid and the like may be detected
by decomposing the soap with hydrochloric or nitric acid and then testing
the acid aqueous liquid.

One of the commonest medicinal soaps contains carbolic acid. To
 determine the proportion of the phenol, 5-10 grams of the soap are dissolved
in water with addition of caustic soda, the solution shaken with ether and
the aqueous liquid treated with excess of sodium chloride to precipitate
the whole of the soap. The liquid is then filtered and the insoluble residue
washed with saturated sodium chloride solution, the liquid being then
acidified with dilute sulphuric acid and the phenol estimated by means of
bromine (see Carbolic Acid, p. 330).

(/) MINERAL AND RESIN OILS, PARAFFIN WAX, TURPENTINE, ETC.
These may be detected by extraction of the soap with ether. In most
cases, mixtures of soap with mineral or resin oils, vaseline and the like,
constitute lubricants or cart-grease, analysis of which is dealt with in the
article on Lubricants (see p. 365).

GLYCERINE

Crude glycerine (saponification, soap-lye or distillation glycerine] forms a
yellowish or brown liquid with a repellent odour and an acrid taste, while
purified glycerine (refined, distilled or double distilled, for dynamite] consists
of a colourless or almost colourless, odourless, syrupy liquid with a sweet
taste.

Analysis of commercial glycerines includes qualitative tests to ascertainthe surface of the foot-note.mately N/40 solution) and the titer,